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BACKGROUND: Knowing the pathological changes of the lungs after the wallop from the bullet wound helps to improve the method or mean of dealing with the wound or to reduce the damage to lung functions after the wound.OBJECTIVE: To probe into the functional and pathological changes of the lung tissues after bullet wound.DESIGN: Open experimental study of the animals.SETTING: Department of the Integrated Traditional Chinese and Western Medicine, General Hospital of the Chinese People's Armed Police Forces.MATERIALS: The experiment was completed from June 2003 to December 2003 at the General Hospital of the Armed Police Forces. Six healthy grown-up cross-bred dogs, half male and half female, weighing ( 16.3 ± 0.58 ) kg, aged (8 - 12) months old, were provided by the Experimental Animal Center of the Military Academy of Sciences of Chinese PLA. Animal Center's license No. Was SCXK(army)2002-001. The animals were fed with water and food with no restrictions in an environment in which the temperature was 22 to 23 ℃ and the humidity was 74% - 80%.METHODS: Grown-up healthy domestic dogs were shot at the thick muscular part of their left hind legs with a size 81 automatic rifles, 7.62 mm in caliber and bullet of type-560. Caution was taken to avoid damage to the major vessels and the bone tissues. The shooting distance was 5 meters. Immediate hemostasis and bandaging were performed after shooting. And 6 hours later, pathological examination of the lungs was carTied out.MAIN OUTCOME MEASURES: Pathological changes of the lungs.RESULTS: After the bullet wound, the main pathological manifestations of the lungs were detelectasis of the pulmonary alveoli and the decrease of air volume complicated with inflammatory alveoli infiltration, lung edema, obscure structure of pulmonary alveoli, passive congestion of the small blood vessels, etc.CONCLUSION: The lung wound was obvious after bullet wound and its mechanism was associated with stress, inflammatory reaction of the adjacent tissues and far domino effect. Blood rheological changes after the wound were one of the most important factors to affect the microcirculation of the cerebral and lung tissues. It was found that clear blood rheological changes occurred at the earlier stage after the wound, and the chief manifestations included the increase of the whole blood viscosity and the index of the erythrocyte aggregation at the time of low sheering rate. The changes reached their peaks 6hours after the wound. On the one hand, because of the increase of whole blood viscosity and the index of erythrocyte aggregation, stasis of red blood cells might happen. And embolism of micro blood vessels in the brain and lungs would change the microcirculation of the brain and lungs. On the other hand, when serious injury of local tissues happens, the body's stress reaction would be strong and secretion and the release of stress hormones and certain active biological small molecular substances would increase, such as nitrogen monoxide(NO), tumor necrosis factor(TNF), endothelin(ET), etc. Their increase would stimulate the micro blood vessels of the brain and lungs and disturb their diastole and constriction functions. After the wound by high-speed projectile, blood flow volume in the animal's cerebral and lung tissues reduced sharply. The micrangium of the brain and lung dilated, and its diameter increased, which resulted in ischemia and hypoxia of the brain and lung tissues, and therefore edema of the brain and lung tissues and hypofunction of the lungs. Therefore, for the bullet wound of the limbs, in addition to dealing with local damage, the brain, the lungs and other important organs should be protected. This provides a theoretical basis for improving the brain and lung function after the bullet wound.